The miniaturization and diversification of semiconductor devices has progressed more and more, and a processing method thereof covers a wide range with respect to each of device structures and production steps. With regard to etching of a substrate, for example, a variety of chemical species, processing conditions and the like has been proposed in accordance with kinds and structures of the substrate material in both a dry etching and a wet etching, and further intensive research and development is in progress.
In particular, when a device structure of CMOS, DRAM, and the like is produced, the technique of precisely etching a prescribed material is important, and as an example thereof, a wet etching which uses a chemical liquid is exemplified. For example, a precise etching processing is required in the production of circuit wiring of a microscopic transistor circuit, a metal electrode material, or a substrate having a barrier layer, a hard mask, and the like. However, etching conditions and chemical liquids, which are applied to a substrate having a variety of metal compounds, have not yet been studied sufficiently.
There are examples of studies on chemical liquids for etching titanium nitride (TiN) applied to a device substrate. For example, Patent Literature 1 discloses a processing liquid which has pH of 6.0 to 8.2 and into which both tetraalkyl ammonium hydroxide and hydrogen peroxide are incorporated.